Resin Mold Volume Calculator
Choose a round or rectangular mould, enter its size and how many you are filling, and get the total resin to mix with an allowance for waste.
How the calculation works
Round: π × (diameter ÷ 2)² × depth. Rectangular: length × width × depth. The volume of one mould is multiplied by the number of moulds and by (1 + waste %).
Example: four round coasters, 4 in across and 1/2 in deep. One holds π × 2² × 0.5 = 6.28 cubic inches, so four hold 25.1 cubic inches. With 10% waste, that is 27.6 cubic inches, about 0.12 US gallons or 15.3 US fl oz.
Once you have the total, split it between resin and hardener with the epoxy mixing ratio calculator.
Estimate only. Check the maximum pour depth for your resin before filling deep moulds.
Frequently asked questions
How do I find the volume of a round mould?
Use the cylinder formula: π × radius² × height, where radius is half the diameter. A 3 in coaster mould filled 1/4 in deep holds about 1.77 cubic inches, or roughly 1 US fl oz.
How much extra resin should I mix for moulds?
Mix 10 to 15% extra. Resin sticks to the cup and stir stick, and silicone moulds are rarely filled to a perfect line.
Does this work for curved or irregular moulds?
Not exactly. For irregular shapes, fill the mould with water, pour the water into a measuring jug, and use that volume as your resin volume. It is the most accurate method.
Can I mix different mould sizes together?
Yes. Calculate each size separately and add the results, then mix everything in batches that stay within the working time of your resin.